Mongoose aggregate and group by two fields - mongodb

Question

I want to aggregate a table to lookup in other 3 tables, then make a nested group by.
I have 4 models
Order
Order_Batches which have a ref to order
Batch which have a ref to Order_Batch
Event which have a ref to Batch
so i'm selecting all orders then getting all it's orderbatches then find all batch and get all events done on that batch
Code
let order=await Order.aggregate([
{$lookup:{from:'orderbatches',localField:'_id',foreignField:'order',as:"order_batches"}},
{$unwind: {path: "$order_batches", preserveNullAndEmptyArrays: true}},
{$lookup:{from:'batches',localField:'order_batches._id',foreignField:'orderBatches',as:"batches"}},
{$unwind: {path: "$batches", preserveNullAndEmptyArrays: true}},
{$lookup:{from:'events',localField:'batches._id',foreignField:'batch',as:"events"}},
{$group: {
_id: "$_id",
code: {$first: "$code"},
order_batches: {$push: {
batches: "$batches",
events:"$events"
}}
}},
]);
Output
{
"success": true,
"orders": [
{
"_id": "5a5cbdd91ecaff0f8417a10d",
"code": "0",
"order_batches": [
{
"batches": {
"_id": "5a5cbdd91ecaff0f8417a114",
"updatedAt": "2018-01-15T14:42:33.585Z",
"createdAt": "2018-01-15T14:42:33.585Z",
"number": 1,
"quantity": 10,
"orderBatches": "5a5cbdd91ecaff0f8417a10e",
"removed": false,
"__v": 0,
}
"events": []
},
{
"batches": {
"_id": "5a5cbdd91ecaff0f8417a116",
"updatedAt": "2018-01-15T14:42:33.586Z",
"createdAt": "2018-01-15T14:42:33.586Z",
"number": 2,
"quantity": 10,
"orderBatches": "5a5cbdd91ecaff0f8417a10e",
"removed": false,
"__v": 0,
}
"events": [
{
"_id": "5a5cbdd91ecaff0f8417a117",
"updatedAt": "2018-01-15T14:42:33.587Z",
"createdAt": "2018-01-15T14:42:33.587Z",
"batch": "5a5cbdd91ecaff0f8417a116",
"process": [
"5a5cbdd91ecaff0f8417a115"
],
"removed": false,
"__v": 0
}
]
}
]
}
]
}
Expected Output
{
"success": true,
"orders": [
{
"_id": "5a5cbdd91ecaff0f8417a10d",
"code": "0",
"order_batches": [
{
"batches": {
"_id": "5a5cbdd91ecaff0f8417a114",
"updatedAt": "2018-01-15T14:42:33.585Z",
"createdAt": "2018-01-15T14:42:33.585Z",
"number": 1,
"quantity": 10,
"orderBatches": "5a5cbdd91ecaff0f8417a10e",
"removed": false,
"__v": 0,
"events": []
}
},
{
"batches": {
"_id": "5a5cbdd91ecaff0f8417a116",
"updatedAt": "2018-01-15T14:42:33.586Z",
"createdAt": "2018-01-15T14:42:33.586Z",
"number": 2,
"quantity": 10,
"orderBatches": "5a5cbdd91ecaff0f8417a10e",
"removed": false,
"__v": 0,
"events": [
{
"_id": "5a5cbdd91ecaff0f8417a117",
"updatedAt": "2018-01-15T14:42:33.587Z",
"createdAt": "2018-01-15T14:42:33.587Z",
"batch": "5a5cbdd91ecaff0f8417a116",
"process": [
"5a5cbdd91ecaff0f8417a115"
],
"removed": false,
"__v": 0
}
]
}
}
]
}
]
}
I've done this but also not working
let order=await Order.aggregate([
{$lookup:{from:'orderbatches',localField:'_id',foreignField:'order',as:"order_batches"}},
{$unwind: {path: "$order_batches", preserveNullAndEmptyArrays: true}},
{$lookup:{from:'batches',localField:'order_batches._id',foreignField:'orderBatches',as:"order_batches.batches"}},
{$unwind: {path: "$order_batches.batches", preserveNullAndEmptyArrays: true}},
{$lookup:{from:'events',localField:'order_batches.batches._id',foreignField:'batch',as:"order_batches.batches.events"}},
{$group: {
_id: "$order_batches._id",
// code: {$first: "$code"},
"batches": {
"$push": "$order_batches.batches"
}
}},
{$group: {
_id: "$_id",
code: {$first: "$code"},
"order_batches": {
"$push": "$order_batches"
}
}},
]);

Answer 1

I got it to work
let order=await Order.aggregate([
{$lookup:{from:'orderbatches',localField:'_id',foreignField:'order',as:"order_batches"}},
{$lookup:{from:'styles',localField:'style',foreignField:'parent',as:"style"}},
{$lookup:{from:'processes',localField:'style._id',foreignField:'style',as:"processes"}},
{$unwind: {path: "$order_batches", preserveNullAndEmptyArrays: true}},
{$lookup:{from:'batches',localField:'order_batches._id',foreignField:'orderBatches',as:"order_batches.batches"}},
{$unwind: {path: "$order_batches.batches", preserveNullAndEmptyArrays: true}},
{$lookup:{from:'events',localField:'order_batches.batches._id',foreignField:'batch',as:"order_batches.batches.events"}},
{$group: {
_id: "$order_batches._id",
order_id: {$first: "$_id"},
code:{$first:"$code"},
processes:{$first:"$processes"},
style:{$first:"$style"},
"batches": {
"$push": "$order_batches.batches"
}
}},
{$group: {
_id: "$order_id",
"code":{$first:"$code"},
"style":{$first:"$style"},
processes:{$first:"$processes"},
"order_batches": {
"$push": "$batches"
}
}},
]);